The coroner, Brandt Shortland, said the condition of the family's state house in Otara may have been a factor in the death of Emma-Lita Bourne, who was suffering from pneumonia when she died from a brain bleed.

Professor Michael Baker, from the University of Otago, specialises in environmental health and housing, and is also a medical doctor.

He said, given young children spend about 90 percent of their time at home, the health and safety of that environment was critical to their wellbeing.

Dr Baker said previous research had shown a strong link between respiratory disease and living in cold and overcrowded housing.

He said low income families in Aotearoa were typically living in rental housing which was of lower quality than owner-occupied housing - and something needed to be done.

"Putting all of this together, there is a very strong case for a basic housing warrant of fitness for rental housing," he said.

"At the very least, this should be a requirement for all social housing which receives government funding, which would include Housing New Zealand properties and those occupied by people receiving the accommodation supplement."

He said, last year, the University of Otago collaborated with the New Zealand Green Building Council, ACC and five councils to pilot test a housing warrant of fitness (WOF).

"This test showed that WOF was practical and acceptable. It also showed that the majority of properties had defects, but that many of these could be easily rectified," he said.

"Our published research has shown that there are highly significant health benefits from three essential upgrades, insulation, efficient heating, such as heat pumps, and home safety improvements."

He said other research has identified the importance of reducing household crowding for protecting children from serious infectious diseases.

Dr Baker is currently leading a national case-control study to investigate risk factors for rheumatic fever, which investigates a range of housing risk factors including crowding, cold, damp and mould exposure.

Last month, the Minister Responsible for Housing New Zealand, Bill English, called on the agency to act quickly to ensure people were not living in unhealthy state houses.

Mr English said there was now much better use of information to ensure families, with children who had rheumatic fever for instance, were properly housed.

He said Housing New Zealand had spent a lot of time and money upgrading its housing, but more had to be done.